src/java.desktop/unix/classes/sun/awt/X11/XMenuBarPeer.java

@@ -294,11 +294,11 @@
     /**
      * @see XBaseMenuWindow#getSubmenuBounds
      */
     protected Rectangle getSubmenuBounds(Rectangle itemBounds, Dimension windowSize) {
         Rectangle globalBounds = toGlobal(itemBounds);
-        Dimension screenSize = Toolkit.getDefaultToolkit().getScreenSize();
+        Dimension screenSize = graphicsConfig.getBounds().getSize();        
         Rectangle res;
         res = fitWindowBelow(globalBounds, windowSize, screenSize);
         if (res != null) {
             return res;
         }